16 
THE VOYAGE OF H.M.S. CHALLENGER. 
The otocysts are situated on the ventral face of the central nervous system, between 
the pedal and visceral ganglia ; each of them encloses a number of otoliths (PI. II. 
fig. 9, cl). 
Osphradium . — The right pallial nerve (i, in the figures of the central nervous 
system) bifurcates shortly after its origin. Its posterior branch leads to a ciliated pad, 
situated on the inner face of the mantle. This pad, nervous in its nature, is the 
osphradium, which has the same position and structure in Clio as has been represented 
by Gegenbaur in Cavolinia. Its deeper portion is a ganglionic band with numerous 
cells, whilst the superficial portion consists of an epithelium with ciliated columnar 
cells. 
2. Cuvier ina. 
The Head and Foot . — In this genus the head and tentacles agree with those of 
Styliola and Hycdocylix, and the fins with those of Styliola and Clio (s. str.). The 
posterior lobe of the foot resembles that in the two latter subgenera, but is somewhat 
notched in the centre of its free border (PI. II. fig. 6, h). 
The Mantle . — The mantle-opening, like that of Clio (subgenus Clio, s. str.) is as large 
as the opening of the shell, the margins of the mantle being entirely separated. 
The shield (pallial gland) is long, and is divided into two halves by a transparent 
transverse band, like that of Hyalocylix, but it does not exhibit the two small latero- 
anterior portions of this latter. As for the lateral lobe of the mantle (balancer), situated 
here, as in all Cavoliniidse, on the right side, it is somewhat reduced, and does not arise 
from the very border of the mantle but a little within it ; on the other side, in an almost 
symmetrical position, is another appendage somewhat similar to it and of almost the same 
size. The columellar muscle is very large. 
The Digestive Tract . — An examination of this part of the body shows that the jaws, 
closely resembling those of other Cavoliniidse, are well developed, and that the radula is 
proportionally longer than in other Thecosomata. The salivary glands resemble in shape 
those of other Cavoliniidse, but are much larger. 
The oesophagus, at a little distance from the buccal mass, traverses a partition 
(PI. II. fig. 6, f) which exists indeed in all Pteropoda. The stomach and liver are like 
those of Styliola and Clio (s. str.), but I have seen no gastric caecum. 
The flexure of the intestine is lateral in Cuvierina, as in all Thecosomata, and to 
such an extent that the oesophagus and intestine are here almost in the same longitudinal 
plane, and not at all in the same sagittal plane. 
The anus is situated far forward, near the mantle-opening, as in Clio ( s . str.). It 
presents an anal gland as in other Cavoliniidse. 
The Circulatory and Excretory Organs. — Cuvierina has no gill any more than Clio, 
